Renewable energy power systems, such as wind energy power systems and solar energy power systems, often include a power converter with a regulated DC bus. For example, wind power systems, such as wind driven doubly-fed induction generator (DFIG) systems or full power conversion systems, can include a power converter with an AC-DC-AC topology. Solar power systems can include a power converter that has a DC-DC-AC topology.
An energy storage system can be coupled to the DC bus of a power converter in a renewable energy system. The energy storage system can be used, for instance, to apply power to the DC bus of the power converter during transient conditions. A switching power supply can be provided to transfer energy back and forth between the DC bus of the power converter and the energy storage device. For instance, the switching power supply can include a DC to DC converter configured to convert a first voltage on the DC bus to a second voltage at the energy storage device, and vice versa. It can be desirable for the switching power supply to be bi-directional to allow not only for power flow from the energy storage device to the DC bus during transient conditions but also to allow power flow from the DC bus to the energy storage device, for instance, to charge the energy storage device.
A need exists for an improved switching power supply for an energy storage system that provides for the more efficient transfer of energy between the energy storage system and the DC bus of a power converter. A switching power supply that provides for improved bi-directional power flow between the energy storage system and the DC bus would be particularly useful.